Four people who were injured by falling rocks at Red Rocks Amphitheatre in September 2011 are suing the City of Denver, which owns Red Rocks. In all, seven people were hit by rocks during the encore of a Sound Tribe Sector 9 show, but only four have filed lawsuits. They claim that the city was lax in its efforts to prevent such an incident. Even though the engineers hired by the city repeatedly recommended that the rocks be inspected and maintained every year, city officials didn't follow that advice.

The city's attorneys have asked that the lawsuit be dismissed. They argue that Denver can't be held liable because it's protected under the Colorado Governmental Immunity Act, which was designed to shield cities and towns from gratuitous personal injury lawsuits. But in August 2013, a judge rejected that argument and declined to dismiss the lawsuit. The city is now appealing the judge's decision to the Colorado Court of Appeals.